History of aspiration was present in 93.1% of children,asthmatic wheeze in 67.8%,retraction during inspiration in 40.2%,cyanosis in 27.6%,hoarseness in 19.5% and audible stridor in 4.6%.

• 1%25有异物吸入史；喘鸣占67.；8%25、吸气性凹陷40